Alkylation of phenols



United States Patent 3,409,678 ALKYLATION 0F PHENOLS' Hans L. Schlichting, Grand Island, and Anthony D. Barbopoulos and Walter H. Prahl, Buffalo, N.Y., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y.,

a corporation of New York No Drawing. Filed Nov. 19, 1965, Ser. No. 508,822 3 Claims. (Cl. 260-621) ABSTRACT OF THE DISCLOSURE Alkylated phenolic compounds are ing in the vapor phase a mixture of an alkyl aryl ether,

This invention relates to a process for preparing alkylated phenols. More particularly, the invention relates to a catalytic vapor-phase process for preparing alkylated phenols.

It is known that alkyl aryl ethers such as ether may be transformed in the vapor phase,

to the formation of numerous well as non-selective substitution.

Selectively substituted phenols are commercially desir- It is an object of the present invention to provide an improved process for preparing alkylated phenols. Another object of this invention is to provide a process whereby improved selective positioning of the alkyl subproduct, e.g., the selectively alkylated phenol, is thereafter recovered from the reaction mixture.

From a further description of the invention, it will be readily apparent that the novel processoffers numerous advantages. The presence of 3,409,678 Patented Nov. 5, 1968 position, preferably ortho, is of 6 to 16 carbon atoms, preferably of 6 to 12 carbon atoms, alkyl is of 1 to 10 carbon atoms, preferably of 1 to 6 carbon atoms, and the combined carbon content of the molecule does not pylphenylethers, nonyl butylphenyl ethers, and the like.

The alumina catalysts espectially useful in the practice of the invention comprise the aluminum oxides having extensive surface areas and great adsorptive capacities. Such alumina may be obtained from natural sources or may be prepared synthetically, as described, for instance, in Catalysis," vol. I, Emmett, 327 (1954).

hydrogen chloride concentration in the reaction zone may also be used. However, anhydrous or aqueous hydrogen bromide may also be utilized.

The hydrogen halide employed as the catalyst activator may be introduced to the reaction in molar proportions based on a molar proportion of alkyl aryl ether and may range rom 0.005:1 to 1:1, preferably 0.01:1 to 0.05:1.

Residence time in the reaction zone may be greater than about one minute, but preferably the residence time is maintained between 5 seconds and 20 seconds. Suitable operating temperatures for the reaction the foregoing temperatures represent the preferred temperatures, generally they may vary depending upon the vaporization temperatures of the reactants. Although the pressure of the reaction is maintained at atmospheric pressure, it is within the scope of this invention to employ subatmospheric and superatmospheric pressures, depending upon the design of the reactor.

The process of the invention may be carried out in any suitable catalytic reaction chamber packed with grains or pellets of alumina catalyst, as such or in com- Advantageously, a vertical column packed with alumina catalyst and adapted to receive the feed stream, for instance, at the top and discharge the effiuent at the bottom may be effectively employed. In some instances, it

is possible to employ a fluidized bed reactor, wherein the catalyst is in a fluidized form. Additionally, it is within the scope of the invention to utilize other known and convenient methods.

The efiiuent of the reaction zone is processed so as to separate the alkylation product. Suitable methods for the separation of said reaction product from the reaction mixture include distillation, fractionation or extraction.

It is also within the scope of this invention to prepare o,o-alkylated phenols by passing an aryl alkyl ether,

according to the process xylenol may be prepared by passing anisole,

and hydrogen chloride over the reaction zone catalyst.

The following examples are presented to further illustrate the novelty and utility of the present invention but not with the intention of unduly limiting the otherwise indicated, all temperatures are in grade and all parts and percentages are EXAMPLES 1-3 same. Unless degrees centiby weight.

The advantageous effects of the presence of small amounts of hydrogen chloride on the rearrangement of anisole in the presence of alumina catalyst to form o-cresol are demonstrated by the following three examples conducted under the hereinafter mentioned and listed conditions. One reaction mixture contained hydrogen chloride in accordance with the present invention. The

other two were run for comparison purposes.

Three reactors were activated alumina granules and heated and controlled salt baths.

In Example 1 a mixture containing a 1.0 portion oi anisole and drogen chloride was continuously ted to each packed with 400 par placed in electrically ts of molar proan .019 molar proportion of hythe reactor. In 2 and 3 only anisole was continuously fed to the reactors. The efliuent stream of all three reactors was collected as condensate and analyzed by gas chromatography. The following table gives the reactants, amounts,

and reaction conditions employed as well as giving the results obtained:

EXAMPLE 1 Feed:

Anisole parts HCl gas do Temperature C-.. Condensate:

Anisole parts.. Phenol do o-Cresol do m-Cresol de p-Cresol do Xylenols do. High boilers do Conversion of PhOMe percent....

EXAMPLE 2 Feed:

Anisole parts HCl gas Temperature C Condensate:

Anisole "parts" Phenol do o-Cresol do m-Cresol do p-Cresol do Xylenols ....do High boilers do Conversion of PhOMe percent EXAMPLE 3 Feed:

Anisole "parts" HCl gas Temperature C Condensate:

Anisole parts 162 Phenol do 188 o-Cresol do 240 m Cresol do 71 p-Cresol do 90 Xylenols do. 185 High boilers do 75 Conversion of PhOMe percent.

The reaction temperature of Example 2 was adjusted to obtain the same 99 percent conversion as in Example L'AdVantageously, in accordance with the process of the invention (1) the same percent conversion of anisole was obtained at a lower temperature, that is, at 300 degrees centigrade in Example 1 as compared to Example 2 at 320 degrees centigrade; (2) a substantial selectivity to ortho-substitution over metaand para-substitution is clearly shown by Example 1, wherein 99.2 percent of the mono-substituted products is o-cresol, as compared to 60.2 percent in Example 2 conducted in the absence of hydrogen chloride; and (3) yields of desirable products, such as o-cresol, m-cresol, p-cresol and Xylenols, was increased as shown by the reduction of the yield of 14.0 percent high boilers in Example 2 to a yield of 6.8 percent of high boilers in Example 1 which was conducted in the presence of hydrogen chloride.

When anisole in Example 1 is replaced by a compound such as phenetole, butyl phenyl ether, pentyl phenyl ether, nonyl phenyl ether or the like, similar ortho-alkylation occurs, producing the corresponding ortho-alkylated phenol (2- or o-alkylated phenol).

It is also apparent that when anisole in Example 1 is replaced by a compound such as o-methylanisole, o-ethylanisole, o-methylphenetole, hexyl o-ethylphenyl ether, nonyl o-butylphenyl ether, or the like, similarly orthoalkylation occurs, producing the corresponding orthoalkylated phenol (2,6- or o,o-alkylated phenol).

From the foregoing description and examples, it is apparent that various modifications are possible within the scope of this invention and it is therefore not to be construed as limiting the invention except as defined by the appended claims.

What is claimed is:

for the production of alkylated phenolic compounds comprising passing in the vapor phase a mixture of an alkyl aryl ether selected from the group consisting of anisole and o-methylanisole, and a small but effective amount of a hydrogen halide selected from the group consisting of hydrogen chloride and hydrogen bromide in molar proportions based on the aryl alkyl ether ranging from 0.005 to 121, over an alumina catalyst at a temperature from about degrees centigrade to about 350 degrees centigrade, and separating the alkylation product from the reaction mixture.

2. A process in accordance with claim 1 wherein the alkyl aryl ether is anisole.

3. A process in accordance with claim 1 wherein the alkyl aryl ether is o-methylanisole.

References Cited UNITED STATES PATENTS 1,876,435 9/ 1932 Schollkopf et a1. 260-621 2,289,886 7/1942 Schmerling 260-621 LEON ZITVER, Primary Examiner. H. ROBERTS, Assistant Examiner. 

